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RE: st: : RE: list command

From   "Nick Cox" <>
To   <>
Subject   RE: st: : RE: list command
Date   Mon, 4 Aug 2008 17:53:40 +0100

Not quite. 

-egen, count()- does not count distinct values. It counts non-missing
values, regardless of whether they are the same or different. 

See the references in my previous post in this thread. 


Steven Samuels

I think that Daniel's second example would be:
> Ndc: 00904161260  gpi: 44300040007440
>      00904161260  gpi: 44300040007441

and that he wants to list instances where the same NDC has 2 or more  

If so:

bysort ndc (gpi): gen count=_N   // counts number of observations  
with the same ndc
list  ndc old_ndc e49_ gpi g64_  if count>1

egen count= count(gpi), by(ndc)

list  ndc old_ndc e49_ gpi g64_  if count>1

If the same ndc gpi combination is listed more than once in the data,  
Daniel should first:

bysort gpi ndc: keep if _n==1

On Aug 4, 2008, at 11:51 AM, Daniel Sepulveda-Adams wrote:

> OK here is an example of what happened in the dataset, this dataset  
> is a
> drugs description, therefore codes are associated to names and  
> strength the
> drug and packages size, etc.
> Ex:
> 1) ndc (National Drug Code) assigned one gpi (Generic Product  
> Identifier)
> ndc: 49502007412   gpi: 44100010102005
> 2) ndc that has more than one gpi (9 in this specific case, why  
> because each
> gpi represent a different packages size)
> Ndc: 00904161260  gpi: 44300040007440
> Please let me know if that clarified my question and thank you for  
> your
> help.

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